Art of making liquid-tight containers



June R. M. BERGSTEIN 2,244,282

ART OF MAKING LIQUID-TIGHT CONTAINERS Filed Dec. -l9, 1938 5 Shets-Sheet1 IN VENTOR. 1 80551 7 MAM/.5 file/gas rev/v.

ATTORNEYS- June 3,1941. R, BERGsTElN v 2,244,282

ART OF MAKING L IQUID-TIGHT CONTAINERS Filed Dec. 19, 1938 3Sheets-Sheet 2 ATTORNEYS.

un 3, 1941. R. M. BERGSTEIN v 2,244,282

ART OF MAKING LIQUID-TIGHT CONTAINERS Filed Dec. 19, 1938 3 Sheets-Sheet3 IN VEN TOR.

ATTORNEYS.

Patented June 3, 1941 UNITED STATES PATENT" OFFICE ART OF MAKINGHQUlD-TIGHT CONT ' Robert Morris Bergstcin, Cincinnati, Ohio'Application December 19, 1938, Serial No. 246,575

8 Claims. (Cl. 93-594) 'In the past, liquid-tight containers, made ofwaxed or paraillne treated stock, and suitable for various liquids orwet food products, such as milk, cottage cheese, etc., have generallybeen handled inone of two ways. The most common of the two is that ofsupplying containers to users in erect form, such as for'examplecylindrical spiral-wound containers that have been. paramned or waxed.The other way is Just by the provision of elaborate and expensivemachinery which is installed in the user's plant, as for example in adairy, which is designed to erect cartons made of untreated board, andcarry these through a paraflln bath or spray, and finally through achilling chamber and on through to the final stages of the operation. Itis obvious that both of these methods have serious objections, in thefirst case, for example, the high cost of transporting, storing andhandling of erect containers, and in the second case the investment,maintenance, and supervision required to install and operate a large.and complex assembling and treating machine at the point of use.

Up until the present time there has been no other practical manner ofsolving such a container problem, due to the absence of simple andeffective ways of obtaining a liquid-tight closure in containers made ofwaxed or paraflin treated stocks. It is in this direction that myinvention as herein disclosed is specifically directed, and it is anobject of my invention to supply wax treated or otherwise waterproofcontainers in flat knock-down form, which may be simply and easilyerected by the user into a sturdy, liquid-tight container. Anotherobject of my invention is to supply flanged caps adaptable for endclosure of carton bodies, which caps are precoated with a thermoplasticadhesive capable of being securely adhered to waxed surfaces in thepresence of heat. A still other objects of myinvention will become ap-.

parent as the description proceeds, the nature and scope of my inventionbeing set forth in the claims which form part of this specification.

In the drawings: I

Figure 1 illustrates a form of my closure cap, which is made ofbox'board or the like, treated on one surface with a coating ofthermoplastic adhesive, as indicated by the shaded portions.

Fig.2 illustrates an alternative form of closure cap, having auxiliaryflanges as indicated.

Fig. 3 illustrates the cap shown in. Fig. 2, somewhat in perspective,with the folds partially broken, in which semi-erect form the caps maybe shipped, nested, if desired.

Fig. 4 illustrates the closure cap shown in Fig. l, with-the addition ofan extra dab or globule of thermoplastic coating adjacent the comers, asindicated.

Fig. 5 illustrates a flat folded open-ended tubular body, which can bemade of waxed or further object of my invention is to provide for theprefolding of said closure caps, if desired, to facilitate assembly ofthe container; to provide simple and effective means of inserting thesaid caps into container bodies in the presence of heat to secure saidcaps into position, in such a manner as to make a liquid-tightcontainer; to provide special methods in connection with such closurewhereby leaks at the corners are positively prevented, either throughthe use of the wax coating on the carton body, or thermoplastic coatingon the closure cap, or both, or by the introduction of additional moltenthermoplastic material into the comers. These and water-proof treatedboxboard or the like.

Fig. 6 illustrates, somewhat in perspective, the carton body shown in;Fig. 5, squared up, with the closure cap shown in Fig. ,2 inserted andsecured in closing position, showing the appearance of the end closureat one end of the container.

Fig. '7 is a diagrammatical illustration of a machine adaptable forfeeding out, folding and inserting, and thereafter sealing by means ofheat the closure cap into position at one end of the carton body. I

Fig. 8 illustrates a detail of the male die used in connection with themachine illustrated in Fig. 7, showing the cut-away portions of same atthe corners. I

Fig. 9 is a detail of an alternate form of die, which is expansible infour directions.

Fig. 9a is a section taken along line 9a-9a' of Fig. 9.

Fig. 10 illustrates a further alternative form of male die, showing aspecial flanged rim which upon expansion of the die, corresponds to agroove in the female die element.

Fig. 11 is a diagrammatic illustration of an alternate cap-insertingdevice, which provides for a shot of molten thermoplastic material intothe corner portions, upon insertion of the cap.

Fig. 12- illustrates a form of my container wherein one end'has beenclosed by the cap previously referred to, and the other end closed bymeans of bringing two opposite walls of the container together, theremaining two opposite walls having definite folds to permit infolding,a

separate strip of thermoplastic coated board or paper having beensecuredover the infolded walls, to provide a closure as illustrated.

Fig. 13 is a diagrammatic illustration of the mechanism for applying theclosure strip illustrated in Fig. 12, which mechanism is adaptable tofolding the strip, applying it, in the presence of heat to causepositive adhesion, simultaneously severing the strips to desired unitlengths.

Fig. 13a is a section taken along line l3a-|3a of Fig. 13.

Fig. 14 is an illustration, somewhat in perspective. of an erect, sealedcontainer, made by 4 the mechanism illustrated in Fig. 11.

Before beginning a. detailed description of the drawings, a word mightbe in order regarding the thermoplastic coatings contemplated by myinvention. I have found that paper, or board, or the like, pre-coatedwith certain materials, such as rubber-wax mixtures, or with isobutylenepolymer sold under the trade name of Vistanex, possesses the property ofadhering tenaciously to waxed or parailined surfaces when pressedagainst such surfaces in the presence of heat. Both of these materialscan be coated by what is known as the hot melt method, which consists inthe application of the coating in molten form to the paper, thereafterallowing the coating to cool, although there are other coatings such assynthetic resins which may be applied in solvent form, which, uponevaporation of the solvents, leave a film or coating on the surface ofthe paper which possesses the desired thermo-adhesive properties.

I prefer to have the flanges of closure cap prepared with such athermo-adhesive coating on the surfaces which are brought into contactwith the carton body upon assembly of the container, although if desiredthe entire surface of the cap can be so coated. However, I may alsoapply wax or parailin over the coated surface of the cap, in accordancewith the disclosure in my copending application, Serial No. 43,570,filed October 4. 1935, which has now matured into U. S. Patent2,154,083. issued April 11, 1939, wherein I have shown the principle ofduplex thermoplastic coatings, such as a primary coating of latex and asecondary coating of wax, wherein the presence of heat causes theadhesive properties of the primary coating to take effect through thesuperimposed secondary wax-like coatings.

Fig. 1"illustrates my preferred form of closure cap, the shaded areasdesignating the coated portions as above described. The cap consists ofa main body panel blank i, to which is articulated by the lines of fold2, the side walls 3.

Fig. 2 illustrates an alternate form of closure cap, the same asillustrated in Fig. 1, except with the addition of auxiliary flanges twhich are articulated to the flanges as shown by score lines 5.

Fig. 3 illustrates the closure cap'shown in Fig. 2 on which the foldinghas been partially carried out, leaving the cap in semi-erect conditionas illustrated. It will be observed that the base flanges, that is theflanges 3 articulated to the main body panel, have been folded upwardlyalong thelines of fold number 2, and the auxiliary or secondary flanges4 have been folded reversely along the fold lines-5. The device adaptedto the partial erection of the closure cap into this form if it ispre-folded for shipment into the semierect form as illustrated.

Further, in my description, is illustrated a complete device adapted totake die-cut and coated closure caps, in flat form, feed these out andinsert these in the presence of heat into the end of carton bodies.However, there are many users of treated liquid-tight containers, suchas soda fountains, delicatessens, etc., where even the installation ofthis comparatively simple device might not be justifled ecenomically. Itis for such smaller users that this partially folded closure cap withauxiliary flanges is particularly adapted, as it will be readilyapparent to anyone skilled in the art that it is an extremely simplematter to insert by hand such a partially folded cap into the end of asquared up carton body. And since in this partially folded form the capscan be" shipped nested, the space required for shipping the caps i notmuch greater than in the flat form, and it is an extremely simple andeasy matter to take the top cap off the nested stack, and insert it intothe end of the carton body, the reversely folded auxiliary flangesserving as a convenient guide to insure the correct positioning of thecap within the carton body. After the cap has been so inserted, anextremely simple device consisting of a male heated die, as for exampleas shown in Fig. 8, with an outer supporting frame or female die,controlled by a simple lever action, is all that is necessary to sealthe cap into position, as when the end of the container is brought intoposition over the male die, the outer or auxiliary flanges will therebybe folded downwardly along the outer surface of the carton body, andboth the inner and outer flanges secured by a simple pressing operationin the presence of heat. In other words, such a device would not requireany feeding or inserting mechanism for the closure cap, which is done byhand, the device merely consisting of the die elements controlled by onesimple motion, to provide the actual adhesion.

Referring now to the closure cap shown in Fig. 4, there is an extra beador globule of thermoplastic coating 6 placed adjacent the cornerportions, as indicated in the drawings. If desired, instead of takingthe form of a separate head at the corner, an extra heavy film could beprovided along the entire line of fold or lines of fold connecting theflanges to the main body panel. Such continuous heavy band of coating atthe desired areas can be provided by having grooves or recessions in theroll which applies the coating to the board, the grooves carrying anddepositing on the paper a heavier film than the balance of the coatingroll applies to the remaining surface of the sheet. By so treating theclosure cap, a surplus amount of coating is provided, which will flowwhen turned into molten form by the heated die used in inserting the capinto closing position on a carton body, such surplus of material tendingto plug the pinholes or crevices at the comers, and assure dependableliquid-tightness.

In Fig. 5, I have illustrated my preferred form of carton body, which isextremely simple in nature. It consists of four main body panels, I, 8,9 and I0, there being a smaller panel or glue seam panel ll articulatedto one of the outer main body panels. This carton body is preferablymade of stock which has been waxed or similarly waterproofed on theinner surface at least, and it is shipped in the flat folded formindicated in the drawing, after having been folded along the score'lines To and 9a and the be turned down, at this time the members 2i glueseam secured to the edge of panel I as shown. I prefer to secure theglue seams to the outer surface rather than the inner surface of thepanel 1 in providing the tubular structure, as in that way the glue seamis not interposed in the interior of the carton body when it is squaredup, but an even unbroken interior of the carton body is provided,providing a better condition for theinsertion of the closure cap.

As can be seen in Fig. 6, the carton b'ody illustrated in Fig. above hasbeen squared up, and one end is shown after my closure cap,asillustrated in Fig. 2, has been inserted and secured in positiontherein. As can be seen, the flanges of the closure cap numbers 3 havebeen secured to the inner surface of the ends of the carton body walls,while the auxiliary flanges 4 which are articulated to saidfirst-mentioned flanges, have been folded down upon the outside of theend of the cartonbody walls, and are secured thereto. This provides arigid and secure closure for the end of the container illustrated andafter being fllled-the'other end of the container may be closed in thesame manner or in any other manner desired.

Referring now to Fig. 7, I have illustrated diagrammatically a mechanismcapable of feeding out one closure cap at a time singly from a stack,folding the flanges thereof, inserting the cap into closing position atthe end of the carton body, and applying heat and pressure to secure theadhesion of the caps to the carton body. Number l2 illustrates a hopperin which a stack of. flat closure caps are placed, represented by numberis. At the base of the hopper, is located a rubber belt Hi, positionedaround two pulleys l5 and It. In this manner the bottom cap of the stackin the hopper is resting directly upon the rubber belt M, audit will beapparent that as the rubber belt moves forward in the directionindicated by the arrow, it will carry with it the lowermost cap,clearance space ll being provided in the hopper to permit the passage ofsuch a single cap at a time. The cap thus carried forward by the rubberbelt is transferred onto a plate l8. Plate l8 has a rectangular orsquare opening l8a somewhat larger than the body panel I of the cap.Extending downward from the four corners of opening l8a are guidemembers i 9 which are so positioned as to engage the shoulders l9b ofthe cap member seen in Fig. 2. I

At the time when the cap is thus placed on top of the plate I8, the maledie element 25 is positioned at the top of its stroke, that is above theupper surface of the cap. And after the cap has been so positionedhowever, as just described, the male die element begins its downwardstroke, which brings the main body panel of the cap down through theopening l8a, simultaneously therewith the flanges of the cap are forcedupwardly, the downward pressure of the male die tending to turn themupward against the edges of the opening.

As the die 25 descends further, the guides l9 engage the shoulders l9bretaining the cap in the position seen at A. As the cap enters at leastpartly into the carton body 20, the auxiliary flanges 4 are turned downand pressed against the carton walls by heated members II. The members2lhave eccentric bearings 2la on shafts 2th and are urged to the relativeposi-' tion therewith as shown by springs 2|c. Move-' ment of shafts 2thto rotate the members 2| downward will cause the auxiliary flanges 4 tostrike the abutments 22 and further movement of shafts 2"), due toeccentrics Zia, will cause inward movement of heated members 2| to pressthe flanges 4 firmly against the carton walls.

Since both the male die element as well as the female die element orsupporting frame, and the folding members for the auxiliary flanges maybe heated by electric heating elements, it is apparent that in themaximum operative position or down stroke, the flanges of the cap willbe pressed in the presence of heat securely against the ends of thecarton body. As previously explained the thermoplastic adhesive coatingswhich are utilized, softener turn to a molten state rapidly in thepresence of heat and by the down stroke or operative position of themechanism, which only requires an'extremely short period of time, theend closure of the container will have been effected.

Since the illustration is merely diagrammatic,

I have not illustrated in detail the drive or timing mechanism used tocoordinate the elements indicated, but these will be coordinated bysimple mechanical means. It is understood, of course, that the entireoperation istimed, the elements as described acting in succession,whereby, in order, a single cap is withdrawn from a stack and positionedover the forming element ,which is arranged above one end of the cartonbody, the plunger thereupon commencing its down stroke, and theauxiliary folders beginning at the proper time for infoldingifthe capwith auxiliary flanges is used, until the foldingxhas been completed anda point of depression reached ,thus completing the sealing of thecapinto'closing position at the end of the cartonbody. Thereafter, ofcourse, the auxiliaryfolders are lifted out of position, the male dieelement is withdrawn byan upward stroke, and the mechanism is thereuponready to insert the succeeding cap in the same order of steps justgiven.

In connection with the mechanism just described it should be noted thatthe auxiliary flanges illustrated on the cap shown in Fig. 2

are offset or set back somewhat from the flangesto which they arearticulated. This leaves an offset or shoulder I9b on the main flanges 3so that if the guides or the female die element or retaining elementsare positioned to this offset, the auxiliary flanges can readily befolded back between these guides, although if desired the auxiliaryflanges may be the same length as the flanges to which they arearticulated, or. smaller than the flanges to which they arearticulated,in any degree desired.

Fig. 8 illustrates a detail of the preferred male die element 25 used inconnection with the machine described above. The over-all dimensions ofthis die' correspond approximately to the 7 length and width of the mainbody panel of the closure cap, and it will be noted that at the cornersthere are cut-away portions 26 as shown.

As a result of this, when the male die is in operative position,pressure is applied to the flanges of the closure cap, but due to thecut-away space there is no pressure at the corners, or contacts of themale plunger at the corners, causing thereby a tendency of the softenedandrnolten material to flow into the corner portions, to plug up thepinholes or openings that may exist at these corner portions.

In Figs. 9 and 9a is illustratedan alternate also is designed to seformof male die, which cure tightness at the corners. In this form,

the die is composed of four separate pieces 21, 28, 29 and 30 mounted onshaft 3! and urged to the position shown by springs 21a. Upon attainingits maximum downward stroke, the tapered portion 3M of the shaftextending into the central opening of the four pieces of the die asshown, causes an expansion of this die in all directions, throwingspecial stress at the corner portions. The pressure thus exerteddirectly at the corners by this expansible die is sufficient topartially flatten out the crease or fold lines at the corners of thecarton body, providing intimate contact between the corners of theclosure cap and the corner score lines of the carton body, and providingthereby a tight seal.

The die illustrated in Fig. is a. modification of the die shown in Fig.9. The principle of expansion is the same, but in addition the outerperiphery or edges 32a of the male die elements are provided with araised rim as indicated by the number 331). In the female die or outerholder is a groove 33a which corresponds to this raised rim. Uponexpansion of the die for sealing, this rim forces the flanges of theclosure cap and the corresponding portion of the carton body partiallyinto the groove, in the female die, which affect counteracts the foldlines of the corners of the carton body at the point where it crossesthe fold lines, providing another means of assuring close and intimatecontact between the cap and the carton body at the corner portions. Ifdesired, instead of being a continuous raised bead or rim around theperiphery of the male die, this bead or rim could extend only aroundeach corner of the male die, with the remaining sides of the male diebeing left fiat, as it is the corner portions this is designed to affectparticularly, setting up a stress, as explained, to counteract-thecorner crease lines of the carton body.

The device illustrated in Fig. 11 differs from the devices shownpreviously, in that an arrangement is provided to fiow or inject moltenthermoplastic material into the corners. As illustrated, the male diehas pipe-like passages 32, these hollowed out openings or pipes leadingto the four lower corners of the die as at 33. Indicated at 34 is asupply line leading to a reservoir of thermoplastic material, which iskept heated by any desired means. The normal gravitational downward flowof the molten thermoplastic material fills the chamber 35 which has aplunger 36 to force the flow of a small amount of the moltenthermoplastic material into the corners of the closure cap. The dieshere shown are carried by an arrangement of levers generally indicatedat 37. The closure cap, formed as in Fig. 3, is placed on the cartonbody and the die assembly moved downward into operating relationtherewith by manual actuation of the handle 38. When the inner diereaches its ex treme downward position, as determined by the depth ofthe cap, continued movement of the handle will cause the tapered portion3la of shaft 3| to expand the die within the cap, and the plunger 36fixed to shaft 3| will force the molten material from chamber into thecorners of the cap. It will be understood that the various members willbe provided with electrical heating elements as necessary for flow ofthe material. By this alternate process, the corner portions arecontainer parts themselves. The use of this arrangement "may bedesirable in certain cases where the container and the closure cap areformed of very heavy board, or for other reasons where the gap at thecorner points will be larger than normal and where the other meanspreviously mentioned would not provide a sufficient amount of surplusthermoplastic material to dependably close these corner openmgs.

Fig. 12 illustrates an alternate application of my principle ofutilizing pre-coated thermoplastic surfaces to obtain liquid-tightcontainer closures. Here the container illustrated has had one endclosed as at 40 by means of the flanged cap previously shown, and whichfor the sake of convenience will be designated as the bottom end. Inthis case, however, two opposite panels or the top end of the container,have been scored to permit an infolding of the remaining two oppositewalls, in a manner that is well known, to permit these two remainingopposite carton body walls to be broughttogether. A separate strip ofpaper or board 4| with a precoating of thermoplastic material ononesurface, which surface is to contact the outer surfaces of the twofolded together carton walls, has been placed over the two foldedtogether carton walls in the vmanner shown, and secured thereto by meansof heat and pressure.

In Fig. 13 is diagrammatically illustrated a mechanism adaptable to formthe closure shown on the container in Fig. 12. Indicated by number 42 isa roll of paper or board, pre-coated on one side, as at 43, with a filmof thermoplastic adhesive. After running over the rollers 44 and 45, theedges of the strip are turned downward to form an inverted U by anydesired means, such as forming plate indicated at 45. At about thispoint the upper ends of the cartons. which have had their mouths broughttogether as described in reference to Fig. 12, are introduced into theinverted U formation of the strip. As the strip and carton progress inthe direction indicated by the arrow, 2. pair of heated pressure rolls41 are arranged to complete the seal. With the arrangement shown, thecartons are carried by conveyor 48, and a pair of knives 49 operatetransversely to sever the strip thus completing the formation asillustrated in Fig. 12. It is understood of course that this operationis carried out in timed relation, by any suitable drive mechanism,whereby successive containers could be rapidly and easily sealed by therepetition dependably plugged by the introduction of thermoplasticmaterial in "heat-softened form taken from a separate reservoir, ratherthan depending upon the softened material or coating on the of theoperations just described.

Fig. 14 illustrates, in perspective, an erect container 50 assembled bythe die illustrated in Fig.

11. Numbers 5| indicate the extra gobs of adhesive which have beenapplied to the four corner portions, securely plugging up any creviceswhich might exist at the corners of the containers.

The mechanisms have been illustrated diagrammatically throughout, toshow the principles involved, and it will be apparent that manyvariations therein are possible, such as the use of the contracting andexpanding dies, without departing from the spirit or scope of myinvention.

By the use of the term pre-coating" I refer to any surface which hasbeen coated and dried, that is a surface which has been so coated as tobe untacky at ordinary temperatures up to about 50 centigrade. I haveused the term "themno adhesive to designate that in the presence of maltemperaturea'a permanent and durable bond is formed between thesurfaces.

Either the surfaces of the flanges which are to come in contact with thecarton. body may be so pre-coated, or the entire surface of the closurecap may be so pre-coated; or if desired a portion of the carton body maybe so treated; in any event at least one of the surfaces which are to beso adhered to each other in the presence of heat will be so pro-coated.If desired, a secondary coating of suitable material may be applied overthe pre-coating just referred to, as for example if it is desired toprotect the edges of the closure cap, the caps may have a primarycoating of thermo adhesive material applied to the flanges, andthereafter the entire caps run through a bath of molten .paraiiin,according to the principle of primary and secondary thermoplasticcoatings mentioned in my copending application previously referred to.

It is also obvious that variations can be made in the constructionsherein disclosed, without departing from the spirit or scope of myinvention. For example, the container can be made in one piece by havingthe edge of one flange of the closure cap articulated to a wall of thecarton body. And if desired the carton .body and the .closure cap couldbe triangular instead of rectangular as illustrated, as anymultiple-wall construction is adaptable to the principles outlineherein.

Among the important features of my invention are the methods of assuringdependable liquid-tightnessin the closure, by plugging up the cornerportions thereof with a molten thermoplastic adhesive. I haveillustrated several alternative methods of accomplishing this importantobjective. One of these is through the use of special dies which eitherprovide pressure adjacent the corners, .by a clearance space at thecorners, force the molten thermo-adhesive material into the cornersthemselves, or which cause a 'positive pressure atthe corner itself, toassure positive contact therein. Another method is by the useof aheavier pre-coating at, or adjacent to, the corner portions, such asbeads or gobs of pre-coated thermoplastic material on the closure caps.It is obvious that if desired these beads or extra thicknesses ofpre-coated thermoplastic material might be applied to the comer folds oradjoining areas of the carton body, and my invention contemplates anysuch variations wherein an additional amount of thermoplastic materialis so Pre-coated that upon the action of heat it will serve to provide asurplus of molten material which acts as a plug for the corners of thecontainer. As also described, still another method of accomplishing thissame objective contemplated by my invention is by the introduction orinjection of separate thermoplastic material in molten form at thecorners of the container, that is through the use of thermoplasticmaterial other than that pre-coated on the surface of the closure cap orcarton body.

It is apparent that many different embodiments of this invention may bemade without departing from the spirit and scope thereof;

therefore it is not intended to be limited except as indicated in theappended claims.

I claim:

1. In a packaging machine, means for inserting a closure cap into anopen end of a waterproof multi-walled tubular carton body, andsequentially related means for injecting a sumcient amount of moltenthermoplastic material into the corner portions of said closure cap tofill any crevices at'said corner portions.

2. A process of constructing a liquid-tight carton which includes thesteps of providing a paperboard tube the inner surfaces at least ofwhich are coated with wax, providing a closure member, the inner surfaceof. which at least is coated with a'thermoplastic rubbery substance ofsimilar appearanceto wax but forming a strong bond therewith whenheated, assembling the closure to thetube while the coatings on both arein non-adhesive condition, and thereafter producing adhesion of thecontacting parts by the application thereto of heat and pressure.

3. The process of claim 2 wherein the coating on the tube is a coatingof paraflin wax and the coating on the closure is a coating ofisobutylene polymer.

4. The process of claim 2 wherein the tube is a tube of polygonal crosssection and the closure is a closure having a base of the same crosssection and flaps attached thereto, said closure being inserted in saidtube with said flaps lying toward the end of said tube into which saidclosure is inserted and paralleling said walls.

5. The process of claim 22 wherein the tube is a tube of polygonal crosssection and the closure is a closure having a base of the same crosssection and flaps attached thereto, said closure being inserted in saidtube with said flaps lying toward the end of said tube into which saidclosure is inserted and paralleling said walls, and in which saidcoating is so applied to said closure member as to be substantiallythicker adjacent corner portions of said base whereby to provide anexcess of the coating for corner seal ing purposesat said cornerswithout impairing the general surface coating of said closure memher.

6. The process of claim 2 wherein the tube is a tube of polygonal crosssection and the r-iosure is a closure having a base of the same crt sssection and flaps attached thereto, said closu'e being inserted in saidtube with said flaps lying toward the end of said tube into which saidclosure is inserted and paralleling said walls, and in which the 'heatand pressure is applied by means of dies having cut-away portions at thecorners thereof and so shaped as to compress softened portions of thecoating on said closure member at least into the comers of the saidclosure.

7. A process of constructing a liquid-tight carton which includes thesteps of providing a paperboard tube the inner surfaces at least ofwhich are coated with wax, providing a closure member, the inner surfaceof which at least is coated with a thermoplastic rubbery substance ofsimilar appearance to wax but forming a strong bond therewith whenheated, assembling the closure to the tube while the coatings on bothare in non-adhesive condition; and thereafter producing adhesion of thecontacting parts by the application thereto of heat and pressure, saidtube being a flat walled tube of polygonal cross section, said closuremember comprising a base oi the same cross section and flangesarticulated to said base and independent of each other, said A flanges,when said closure member is inserted in. said tube, adapted to parallelthe walls therot, the coating on said closure member being suificientlythick to provide an excess when soitened during the application of heatand pressure, a portion of which excess will flow into the con ners ofsaid closure member and seai said corners and meeting portions of saidflanges to said tube.

8. A process of making a liquid-tight container which comprisesproviding a flat walled paper= board tube of polygonal cross section andhaving its inner surfaces at least coated with wax, proaaeaoea viding aclosure member to fit in said tube, said closure member being ofpaperboard and comprising a base of the same shape as the cross section01' the tube. flanges articulated to said base but independent of eachother, said flanges being adapted upon the insertion of said closuremember into said tube to parallel the walls of said tube, and a coatingon at least one side of said closure member of a thermoplastic rubberysubstance of similar appearance to a wax coating but having the property02 forming a strong bond therewith under heat and pressure, insertinssaid closure into said tube, sealing said flanges to the walls of saidtube by the application of heat and pressure and separately supplying amolten thermoplastic material to the cormore of said closure member tofill any crevices at said corner portions.

enema MORRIS Emmi.

